Control System for Mining Machine

ABSTRACT

A mining machine such as a mining shovel includes a digging assembly having an upward extending boom and a dipper arm generally horizontally supported by the boom. The dipper assembly includes a dipper disposed at one end of a dipper arm that can slide in translation with respect to the boom to crowd toward or retract from a vertical bank at the mining site. To translate the dipper assembly, the mining machine includes a crowd system having a crowd motor and a crowd actuator. An electronic controller receives the crowd motor torque, a crowd speed of the dipper assembly, and an inertia parameter associated with the dipper assembly. The electronic controller can determine an approximate location of the dipper with respect to the bank and, in a further aspect, can execute an anti-swing function if the dipper is in the bank.

TECHNICAL FIELD

This patent disclosure relates generally to a mining machine such as amining shovel and, more particularly, to a method of controlling andenabling the machine to dig material at a mine site.

BACKGROUND

Of the various types of machines utilized in mining operations, miningshovels are responsible for digging material from a vertical bank faceor other surface that may be located in a pit at the mine site andtransferring the material such as mineral ore, coal, and overburden to adump truck or other machine for transportation. Mining shovels include aboom that extends upwards into the air and at angle with respect to thebank and a dipper assembly that is supported by the boom. The dipperassembly includes a bucket-like dipper that scoops into, fills with, andremoves material from the bank and that is supported by an elongateddipper arm or handle. To enable the dipper to swing upwardly into thebank, the dipper assembly is supported by the boom in a manner thatallows the dipper arm to pivot and slide with respect to the boom, hencethe dipper assembly has at least two degrees of freedom with respect tothe boom. The pivoting motion of the dipper upwards or downwards withrespect to the boom may be referred to as hoisting. The slidingtranslation of the dipper arm with respect to the boom may be referredto as crowding, when proceeding in the direction of outward extensionfrom the mining shovel, or retraction when proceeding in the directionof inward retraction or motion back towards the mining shovel.

When the dipper impacts and penetrates into the bank filling withmaterial, the mining shovel is subjected to severe forces and stresses.The magnitude of these forces and stresses may possibly damage themechanical components and operational systems of the mining shovel.Further, if the dipper assembly strikes the bank at an incorrect angleof attack, “boom jacking” may occur in which the crowding dipperassembly is pushed back against the boom and may cause the boom to pivotupwardly then drop and bounce with respect to the mining shovel. Toassist operators in controlling the mining shovel to accommodate theseapplied forces, manufacturers often configure mining shovels withcomputer-implemented control systems that regulate the motions and poweroutputs of the mining shovel during the digging operation.

One example of a control system is provided in U.S. Pat. No. 6,466,850(“the '850 patent”). The '850 patent describes a control system whichmonitors various parameters regarding the machine, including a crowdtorque and a hoisting force used for lifting and lowering the dipperassembly into the bank. This information is used in part to controloperation of a crowd motor that is responsible for crowding out andretracting in the dipper assembly to prevent the dipper assembly frombecoming stalled within the bank during a digging operation. The presentdisclosure is directed to providing a control system for a mining shovelor similar machine to similarly assist operation of the machine whendigging.

SUMMARY

The disclosure describes, in one aspect, a mining machine for excavatingmaterial at a mine site or the like. The mining machine can include anundercarriage with one or more propulsion devices and an upper structurerotatably supported to swing with respect to the undercarriage. Toperform the digging operation, a digging assembly is disposed on theupper structure which may include a boom connected to the upperstructure at a lower end and which extends upwardly to an upper end. Thedigging assembly also includes a dipper assembly having a dipper armslidably supported by the boom with a dipper disposed at the first endof the dipper arm. To enable the dipper assembly to slidably translatein the crowd and retraction directions with respect to the boom, a crowdsystem is operatively associated with a crowd motor and a crowd actuatorthat are included with the digging assembly. The mining machine furtherincludes an electronic controller operatively associated with the crowdsystem and in electronic communication with the crowd motor. Theelectronic controller may be configured to calculate a calculated crowdforce and to determine an approximate location of the dipper withrespect to a bank at the mine site based in part on the calculated crowdforce.

In another aspect, the disclosure describes a method of operating amining machine. According to the method, a dipper assembly may slide intranslation with respect to a boom that is arranged in an upwardorientation on the mining machine by operation of a crowd motor. Themethod obtains a crowd motor torque and a crowd speed from the crowdmotor during the sliding translation of the dipper assembly.Additionally, an inertia parameter is assigned to the dipper assembly.The method then calculates a calculated crowd force based in part on thecrowd motor torque, the crowd speed, and the inertia parameter. Themethod can then determine an approximate location of the dipper assemblybased in part on the calculated crowd force.

In yet a further aspect, the disclosure describes an electroniccontroller for a mining machine having a dipper assembly slidablysupported on an upward extending boom and a crowd motor responsible forsliding the dipper assembly with respect to the boom. The electroniccontroller may be configured to perform a crowd force function todetermine a calculated crowd force based in part on a crowd motortorque, a crowd speed of the dipper assembly, and an inertia parameterassociated with the dipper assembly. The crowd force function mayfurther determine an approximate location of a dipper disposed on thedipper assembly based on the calculated crowd force. The approximatelocation may correspond to an in-bank condition and an out-of-bankcondition. The electronic controller may further perform an anti-swingfunction to limit rotation of an upper structure with respect to anundercarriage during the in-bank condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a machine, in the embodiment of amining shovel, including a boom, a dipper assembly, and a crowd systemfor digging material at a mine site and which is configured with anelectronic controller to control the mining shovel according to thedisclosure.

FIG. 2 is a schematic diagram representing an electronic controlleroperatively associated with various other components of the miningshovel for implementing the control system executed by the electroniccontroller.

FIG. 3 is a flowchart representing a possible process or routine fordetermining if a dipper assembly on the mining shovel is digging into abank based on a calculated crowd force applied to the crowd system.

FIG. 4 is a chart representing the crowd forces being generated andapplied during a digging operation.

DETAILED DESCRIPTION

This disclosure relates to mining machines for digging, moving, andunloading material about a mine site as part of a mining operation. Nowreferring to FIG. 1, wherein like reference numbers refer to likeelements, there is illustrated a mining machine of the foregoing typeand, in the particular embodiment, a mining shovel 100 which can beconfigured to crowd into, excavate, and remove material from a verticalface or bank of a pit mine. However, in addition to mining shovels,aspects of the disclosure may be applicable to other mining machines fordigging and excavating such as excavators, draglines, and the like. Theillustrated embodiment of the mining shovel 100 may be mobilized so thatit can move about the mining site during operation but, in otherembodiments, the mining shovel may be temporarily or permanently fixedin location. To allocate mobility and digging functions, the miningshovel 100 may include an undercarriage 102 and an upper structure 104that is supported on the undercarriage. To propel the mining shovel 100over the ground surface 106 of the mine site, that may be disposed belowa vertical face of a bank 108 or pit wall, the undercarriage 102 may beconfigured with one or more propulsion devices such as continuous tracks110, sometimes referred to as caterpillar tracks. The continuous tracks110 form a closed loop that can translate with respect to a frame 112 ofthe undercarriage 102 that includes a drive sprocket, rollers, and/oridlers 114 to facilitate translation of the tracks in a manner to propelthe mining shovel 100. The mining shovel 100 can thus propel itself inthe forward or rearward directions or turn itself towards either side.In an embodiment, multiple continuous tracks 110 can be provided on eachside of the undercarriage 102. In a further embodiment, theundercarriage 102 may include rotatable wheels or other propulsiondevices.

To dig and remove material from the bank 108 or a similar vertical faceat the mine site, a digging assembly 120 may be disposed at the front ofthe upper structure 104 and thus may be referred to as a front end. Thedigging assembly 120 can include a boom 122, which may be an elongated,beam-like structure that is pivotally connected with pins at its lowerend 124 to the upper structure 104. The boom 122 can extend upwardlyfrom the upper structure 104 to its upper end 126 and may be angled inthe forward direction at, for example, a 60° angle. To support the boom122 in its upward extending, angled orientation, one or more suspensionropes 128 can be attached to the upper end 126 and extend back down to aA-frame shaped backstay 129 disposed on the upper structure 104. Theboom 122 can support a dipper assembly 130 that includes a bucket-likedipper 132 that can penetrate into and fill with material from the bank108. The dipper 132 may be supported by a dipper arm 134 or dipperhandle that may be an elongated, arm-like structure that extends betweena first end 136 connected to the dipper and a distal second end 138.During a digging operation, the dipper assembly 130 can swing upwardlyinto the bank 108 while projecting forwardly, or crowding, into thebank. To enable the swinging or scooping motion of the dipper 132 intothe bank 108, the dipper assembly 130 is configured to pivot and slidewith respect to the boom 122.

To facilitate pivoting and sliding of the dipper assembly 130, a saddleblock 140 connects the dipper arm 134 to the boom 122. The saddle block140 can be pivotally connected to the boom 122 at a pivot point 142located between the fixed lower end 124 and the free upper end 126.Hence, when the dipper arm 134 is supported in the saddle block 140, thedipper arm can pivot or articulate with respect to the boom 122, therebymoving the dipper 132 upwardly and downwardly in the vertical direction144 in movements that may be referred to as hoisting or lowering. Toallow the dipper assembly 130 to translate or slide with respect to theboom 122 in the forward-reverse direction 146, the saddle block 140 canform a sleeve or cradle supporting the dipper arm 134 and which engagesthe dipper arm via appropriate bearings, rollers, or the like. Extensionof the dipper assembly 130 in the forward-reverse direction 146 towardthe bank 108 may be referred to as crowding the dipper assembly andretraction of the dipper assembly away from the bank may be referred toas retraction or retracting the dipper assembly.

To cause relative movement of the components of the digging assembly120, the mining shovel 100 can include various motors, actuators, andrigging that are operatively associated with each other. For example, tohoist or lower the dipper 132 in the vertical direction 144, the miningshovel 100 can include a hoist system 150 that is powered by an electrichoist motor 152. The hoist motor 152, which may be an alternatingcurrent (“AC”) motor of suitable power to lift and lower the dipperassembly and the dipper 132 when filled with material, may be disposedin the upper structure 104. To transfer motive power from the hoistmotor 152 to the dipper assembly 130, one or more hoist ropes 154 orcables can be attached to the dipper 132 and extend upwardly and arounda sheave 156 or pulley rotatably disposed at the upper end 126 of theboom 122. The hoist ropes 154 wrap partially around the rotatable sheave156 to generally reverse their direction and extend back down and windaround a hoist winch 158 or drum disposed in the upper structure 104.The hoist winch 158 is operatively coupled with the hoist motor 152.Hence, operation of the hoist motor 152 rotates the hoist winch 158 towind up or pay out the hoist ropes 154 causing the dipper assembly 130to pivot about the pivot point 142 up or down along the verticaldirection 144. The weight of the dipper assembly 130 is partiallysupported by the hoist ropes 154 that also pull the boom 122 in tensionagainst the suspension ropes 128.

To cause the dipper assembly 130 to translate with respect to the boom122 by crowding out or retracting in along the forward-reverse direction146, the mining shovel 100 can also be equipped with a crowd system 160.The crowd system 160 can also be powered by an electric crowd motor 162disposed in the upper structure 104. To convert rotation of the crowdmotor 162 to translation of the dipper assembly 130, the crowd system160 can include an appropriate crowd actuator operatively interconnectedwith the dipper arm 134. In the illustrated embodiment, the actuator maybe a rope system or rigging which includes a first crowd rope 164 and asecond crowd rope 166. The first crowd rope 164 can attach to the dipperarm 134 proximate to the first end 136 and the second crowd rope 166 canattach to the dipper arm proximate to the second end 138. The first andsecond crowd ropes 164, 166 extend along the length of the dipper arm134 back toward the saddle block 140 and can partially wrap around thesaddle block 140 to be redirected toward one or more crowd winches 168or drums disposed in the upper structure 104. The rotatable crowd winch168 is operatively coupled to the crowd motor 162. Rotation of the crowdwinch 168 in one direction will pay out the first crowd rope 164 whilewinding up the second crowd rope 166 causing the dipper assembly tocrowd forward toward the bank 108. Rotating the crowd winch 168 in theopposite direction winds up the first crowd rope 164 while paying outthe second crowd rope 166 thereby retracting the dipper assembly 130.

In a further embodiment, the mining shovel 100 may be configured as ahydraulic mining shovel in which the crowd system 160 is associated withone or more hydraulic cylinders that may be disposed proximate thesaddle block 140 and that can be used to crowd and retract the dipperassembly 130 with respect to the boom 122. In such an embodiment, thehydraulic cylinder functionally replaces the first and second crowdropes 164, 166. The hydraulic cylinder can be operatively associatedwith a hydraulic system in which hydraulic fluid is pressurized byoperation of the crowd motor 162 to extend and retract the dipperassembly 130.

In addition to the crowding and hoisting motions used to dig materialfrom the bank 108, the mining shovel 100 can be configured to swing thedigging assembly 120 about a vertical axis 170, as indicated by thearrow, so the dipper assembly 130 moves horizontally over the groundsurface 106 to and from the bank 108. Swinging the mining shovel can beused to, for example, position the dipper 132 over the body of a dumptruck and release the extracted material. To enable the swinging motion,the upper structure 104 has a rotatable platform 172 or turn table thatrotatable with respect to the upper structure to the undercarriage 102.Hence, the upper structure 104 can swing in either direction over theground surface 106 while the undercarriage 102 remains stationary on theground surface. To provide power for the various motors, systems,continuous tracks, and the like, the mining shovel 100 includes anelectrical system that receives three-phase electrical power through atrail cable 176 from an offboard electrical source and distributes thepower to the motors and other components on the mining shovel. In analternative embodiment, the mining shovel may include an onboard primemover such as an internal combustion engine for combusting andconverting a hydrocarbon based fuel to mechanical power. To accommodatean operator and the controls, gauges, and readouts for operating themining shovel 100, an operator's station 178 can be disposed on theupper structure 104 at a location that provides a view towards thedigging assembly 120.

Referring to FIG. 2, to facilitate and coordinate operation of thevarious components of the mining shovel, the mining shovel can includean electronic control unit (“ECU”) or a computerized or electroniccontroller 200, which is represented schematically with thecorresponding controllable components and devices of the mining shovel.The electronic controller 200 can have any suitable computerarchitecture and can be in electronic communication with the variouscomponents on the mining shovel to send and receive electronic signalsin digital or analog form with the components that enable the electroniccontroller to monitor and regulate the operations and functions of themining shovel. The electronic controller 200 may execute and processfunctions, steps, routines, control maps, data tables, charts, and thelike saved in and executable from computer readable and writable memoryor another electronically accessible storage medium to control themining shovel. To perform these functions and operations, the electroniccontroller 200 can include a processor 202 such as a central processingunit or microprocessor or, in other embodiments, an application specificintegrated circuit (ASIC) or other appropriate processing circuitry. Theprocessor 202 may further include a control unit 206 that is responsiblefor regulating its internal and external operations, such as receivingand loading applications and programs, reading and writing data to andfrom memory, and communicating with the other electronic components ofthe mining shovel. The processor 202 can also include a processing unit208 responsible for executing the instructions associated with theprograms and applications. To enable digital processing of data andexecution of applications and programs, the processing unit 208 can bemade of any of various gates, arrays, and other digital logiccomponents.

To store data for processing and the instructions associated withprograms and applications, the electronic controller 200 may includememory 210 or other data storage capabilities. The memory 210 may befurther separated into instruction memory 212 that stores theinstructions associated with the applications and programs and datamemory 214 that is responsible for storing the data processed by theapplications and programs. The memory 210 can include any suitable typeof electronic memory devices such as random access memory (“RAM”), readonly memory (“ROM”), dynamic random access memory (“DRAM”), flash memoryand the like. In addition to the foregoing types of electronic memory,in a different embodiment, the memory 210 may include magnetic oroptical accessibility. For more permanent storage, the electroniccontroller 200 can also read and write information to and from aseparate database 216. The database 216 can include tables, datastructures, libraries, and the like for organizing information in amanner that can be readily utilized by the electronic controller 200.Although in the illustrated embodiment, the electronic controller 200and its components are illustrated as a single, discrete unit, in otherembodiments, the electronic controller and its functions and operationsmay be distributed among a plurality of distinct and separate componentssuch as electronic control units (“ECUs”), programmable logiccontrollers (“PLCs”), etc.

To interface with an operator of the mining shovel, the electroniccontroller 200 can be operatively associated with and in electroniccommunication with one or more operator input devices such as a joystick220 or the like. The operator can manipulate the joystick 220 to producedigital or analog signals that are used to steer the mining shovel andto control movement of the digging assembly during digging operations.The joystick 220 can include toggles, dials, or buttons 222 to enablefurther input from the operator. To provide the operator with visualinformation regarding the operation and performance of the miningshovel, the electronic controller 200 can also communicate with ahuman-machine interface (“HMI”) that includes a visual display device224 such as a liquid crystal display (“LCD”) and may also include audiocapabilities. The visual display device 224 can be part of a portablenotebook computer 226 located in the operator's station of the miningshovel; however, in other embodiments, the visual display device may beprovided as a permanent installation of the operator station. Examplesof visual information can include machine speed, engine load, electricmotor performance, and the positions and forces being applied to thedigging assembly. The notebook computer 226 can also include a keyboard228 to facilitate its function as a HMI by allowing the operator toenter information and directions to the electronic controller 200. Itshould be noted, however, that the operator controls, inputs, anddisplays illustrated in FIG. 2 are by way of example only and mayinclude different arrangements or controls in different embodiments.

In addition to the operator controls, to receive information about thestatus and operation of the mining shovel, the electronic controller 200can be in electronic communication with various sensors 230 disposedabout the mining shovel and that monitor and measure different operatingparameters. In particular, the sensors 230 can send digital or analogdata to the electronic controller 200 and may include motion ordisplacement sensors, Hall effect sensors, strain or load gages, voltagemeters, current meters, temperature sensors, pressure sensors, and thelike. In the illustrated embodiment, the plurality of sensors 230 caninclude a crowd winch sensor 232 that measures the force or load beingapplied to the crowd winch and a saddle block sensor 234 that measuresactivity of the saddle block such as the pivoting or crowding movementsof the dipper assembly. The sensors 230 can be arranged in networkedcommunication with each other and with the electronic controller 200 ina controller area network (“CAN”) via a bus that physically conducts theelectronic signals; however in other embodiments, communication mayoccur wirelessly through Wi-Fi, Bluetooth, or other communicationstandards.

To direct and control operation of the digging assembly of the miningshovel, the electronic controller 200 can be operatively coupled to theelectric motors associated with the digging assembly and specificallywith the hoist motor 152 and crowd motor 162. The electronic controller200 can process and interpret the control signals or commands inputthrough the joystick 220 and the notebook computer 226 by the operatorand thereby operate the hoist motor 152 and the crowd motor 162accordingly to produce the desired motions on the crowd system and thehoist system. For example, the electronic controller 200 can switch theelectrical power from a generator or the like to the hoist motor 152 andcrowd motor 162 on and off and may reverse the directions of the motorsto pay out or take in the hoist and crowd ropes as desired. To regulatepower to the hoist and crowd motors 152, 162, one or more electricalpower regulators 236 may be disposed between the electronic controller200 and the motors that adjust the applied current and voltage levelsbased on signals from the electronic controller to achieve the desiredoutput speed, torque, and motor direction. In further embodiments, theelectronic controller 200 can also be operatively associated with thehoist winch and the crowd winch to rotatably engage and disengage thewinches from the respective hoist and crowd motors 152, 162.

In addition to operating the hoist and crowd systems, the electroniccontroller 200 can be arranged to swing the upper structure with respectto the lower undercarriage. In particular, the electronic controller 200can be coupled via a motorized arrangement to a gear structure 238 thatis attached to the platform 172 and that can be configured to adjust theforce ratios to accommodate rotating the weight of the upper structure.If the electronic controller 200 receives a swing command from thejoysticks 220, it can motorize the gear structure 238 to horizontallyswing the platform and the upper structure thereon in either direction.Bearings, rail systems, and the like can also be included to enable theupper structure to swing with respect to the undercarriage. As can beappreciated, the electronic controller 200 can be responsible forregulating and controlling other aspects of the mining shovel such asthe continuous tracks used to propel the mining shovel and theelectrical power system that functions as the primary power source forthe mining shovel.

In an embodiment, the electronic controller 200 can be configured toassist the operator in controlling the mining shovel to limit or reducethe affect of the forces generated during the digging operation. Inparticular, these features can take the form of a function, routine, orapplication program including computer executable instructions that canbe stored in the instruction memory 212 of memory 210 and that can beloaded and executed in the processing unit 208 of the processor 202. Forexample, to determine the approximate location of the dipper, whetherthe dipper is located in-bank or out-of-bank, which may or may not beeasy to verify from the operator's station, these instructions caninclude a crowd force function 240. The crowd force function 240 canutilize the information input through and readily obtainable from theother systems of the mining shovel to calculate the actual forces thecrowd system is experiencing in a manner that enables the electroniccontroller 200 to estimate the approximate location of the dipper withrespect to the bank. Further, the electronic controller 200 can beprogrammed to take various actions to assist operation of the miningshovel depending on the determined location of the dipper assembly. Forexample, to prevent unintentional movement of the digging assembly whileit is disposed in the bank, the instructions can include an anti-swingfunction 242 that limits the ability or capability of the upperstructure to rotate with respect to the lower undercarriage.

Referring to FIG. 3, there is illustrated a flowchart of a possiblecomputer executable process 250 or routine for conducting the crowdforce function 240 and anti-swing function 242. Although FIG. 3illustrates a possible sequence as order of steps, steps may be omittedor added and may be performed in any possible alternative order. Theprocess 250 can start with an initialization step 252 in which theprogramming instructions are loaded into the processing unit of theprocessor for execution in the electronic controller. In an embodiment,the mining shovel can be configured to operate in various differentmodes including, for example, a digging mode 254 for conducting thedigging operation and a propulsion mode 256 for propelling the miningshovel over the ground surface about the mine site. Since the process250 needs to be active only during a digging operation, the process canperform a digging assessment step 258 to determine whether the operatorhas selected or enabled either the digging mode 254 or the propulsionmode 256. If the propulsion mode 256 or a different mode is currentlyselected, the digging assessment step 258 can return to theinitialization step 252 until the digging mode 254 is enabled.

If, however, the digging assessment step 258 affirmatively confirms thatthe mining shovel is in the digging mode 254, the process 250 canproceed to a data retrieval or data collection step 260 in which variousdata inputs are collected by the electronic controller. These datainputs can be determined using the sensors operatively associated withthe electronic controller and disposed about the mining shovel. Theelectronic controller may already collect these data inputs inconjunction with the routine operation of the mining shovel. Examples ofthese data inputs can include operator references, commands, or inputsignals 262 from the joystick, crowd speed 264 and crowd motor torque266, and a swing action 268 associated with the rotation of the upperstructure with respect to the undercarriage, and any other suitableinputs. In an embodiment, the swing action 268 may correspond to acommanded swing speed or swing displacement that the operator may beattempting to direct the mining shovel to undertake. The crowd speed 264may correspond to the voltage drawn by the crowd motor and the crowdmotor torque 266 may correspond to the current drawn by the crowd motor.As explained below, in other embodiments, the crowd speed 264 may bemeasured differently. The electronic controller may monitor the datainputs continuously on a real-time basis so that the process 250 isreflective of real-time conditions. The data inputs may be in digital oranalog form.

To perform the crowd force function 240 and estimate the approximatelocation of the dipper with respect to the bank, the process 250 canconduct a calculation step 270 to determine a calculated crowd force 272that can represent the forces being applied to the crowd system. In aparticular embodiment, the calculated crowd force 272 may correspond tothe actual forces and stresses acting on the crowd system, such astension or lack of tension on the crowd ropes separated from otherforces, stresses, or moments being applied or originating elsewhere onthe mining shovel, and may therefore correspond to the forces actingwith respect to the dipper at an instantaneous moment. The calculatedcrowd force 272 can therefore be evaluated to determine whether thedipper is actually in-bank or out-of-bank.

In an embodiment, the calculation step 270 can proceed using thephysical law that force equals mass times acceleration, as determinedaccording to the following equation:

F=M*A   (Eqn. 1)

The variables of the equation, and thus the calculated crowd force 272,are isolated with respect to the crowd system. To provide theacceleration variable, the speed of the dipper assembly moving intranslation with respect to the boom is determined based on the crowdspeed 264 that represents how fast the crowd is paying out or taking upthe crowd ropes. As can be appreciated, the crowd motor speedcorresponds to and can be converted to dipper assembly speed or velocityusing known geometric correlations and dimensions obtained from thestructure of the mining shovel. In another embodiment, the crowd speedor velocity of the dipper assembly may be determined directly by, forexample, measuring translation of the dipper arm with respect to thesaddle block. Directly measuring the speed and/or displacement of thedipper arm with respect to the saddle block may be advantageous in thoseembodiments in which a hydraulic cylinder is utilized to crowd andretract the dipper assembly, as opposed to crowd ropes. The process 250can convert the crowd speed 264 to the crowd acceleration by taking thederivative of the crowd speed, thereby determining the change in speedover time, according to the following equation:

Acceleration=dv/dt   (Eqn. 2)

Hence, through Eqn. 2, the process 250 indirectly calculates the crowdacceleration of the dipper assembly as feedback from readily obtainableinformation such as crowd speed 264 rather than directly attempting tomeasure acceleration of the dipper assembly. The crowd speed 264, andthus the calculated hoist acceleration variable, can be positive ornegative, depending upon whether the dipper assembly is crowding orretracting with respect to the boom and bank, and the units may be inmeters per second² or m/s². To determine the mass variable of Eqn. 1, aninertia parameter 274 can be estimated or determined that is associatedwith the mass of the dipper assembly and other factors. In particular,the inertia parameter 274, representing the resistance to the change inmotion of the dipper assembly with respect to the boom, can be estimatedusing known masses for the dipper assembly and the other components ofthe crowd system as determined during design and manufacture of themining shovel. In some embodiments, the inertia parameter 274 may be astatic value, while in other embodiments, it may vary based onoperational characteristics, component location and the like. The unitsfor the estimated inertia parameter 274 may be in kilograms per meter²or Kg/m².

The forces associated with the crowd system can be calculated accordingto Eqn. 1 above to determine an inertial crowd force 276, which maycorrespond to the total forces needed to accelerate the dipper assemblyin either the crowd or the retraction directions. This can be doneaccording to the following modified version of Eqn. 1:

Inertial Crowd Force=Inertia Parameter*(dv/dt)   (Eqn. 3)

In the embodiments utilizing a hydraulic cylinder to actuate the crowdsystem, the inertial crowd force may be determined based on otherfactors, such as the fluid pressure differential in the hydrauliccylinder between the cap end and the head end of the cylinder instead ofemploying an inertia factor. This quantity may equate to the totalforces being applied to the cylinder by the crowd motor and the dipperassembly. To further isolate the actual forces applied to the crowdropes alone, the inertial crowd force 276 can be subtracted from otherforces being applied to the crowd system from the other components ofthe crowd system. In particular, the other forces may correspond to theoutput torque being generated by the crowd motor. The output torquecorresponds to the crowd motor torque 266 collected during the datacollection step 260. This determination produces the calculated crowdforce 272 according to the following equation:

Calculated Crowd Force=Crowd Motor Torque−Inertia Parameter*CrowdAcceleration   (Eqn. 4)

Or

Calculated Crowd Force=Crowd Motor Torque−Inertia Parameter*(dv/dt)  (Eqn. 5)

The calculated crowd force 272 represents the actual forces beingapplied externally to the dipper assembly, as experienced by the crowdropes, by engagement with the material of the bank, i.e., the net forceson the crowd system minus the torque applied to the crowd system fromthe crowd motor. In other words, the calculated crowd force 272represents the portion of the net total force applied to the crowdsystem that arises from penetration of the dipper into the bank. Thecalculated crowd force 272 may therefore be a better representation ofthe effect of the bank material on the crowd system than the measurementof the crowd motor torque 266, where the output torque may be alsoutilized to overcome frictional resistance of the components of thecrowd system rather than engaging the dipper into the bank.

To ensure that the dipper is actually located in-bank, the process 250can conduct a comparison step 280 in which the calculated crowd force272 is further compared to a crowd force threshold 282. The crowd forcethreshold 282 may be determined based on a predetermined value such as aminimum or maximum quantity or may be determined based on dynamicoperational characteristics regarding the mining shovel and/or minesite. For example, the crowd force threshold 282 can correspond to athreshold value of net forces the crowd system may be anticipated towithstand, or it can be based on a capacity of the crowd motor. In anembodiment, the crowd force threshold 282 can be a percentage of thefull motor torque capacity rating for the crowd motor, such as 100% ofthe maximum rated torque capacity or the maximum continuous stall torqueof the crowd motor. The comparison step 280 can occur according to thefollowing equation:

Calculated Crowd Force>Crowd Force Threshold.   (Eqn. 6)

If the calculated crowd force 272 exceeds the crowd force threshold 282,the process 250 can make an in-bank determination 284 confirming thedipper is disposed within the bank, thereby completing the crowd forcefunction 240. By setting the first crowd force threshold 282 to themaximum rated torque capacity of the crowd motor, the process 250 candisregard incidental or minimal impacts, such as setting the dipper onthe ground surface, that are safely within the capabilities of themining shovel.

In furtherance with the disclosure, in an embodiment, the process 250may proceed with additional steps to perform the anti-swing function 242to limit the operator's ability to swing the upper structure withrespect to the lower undercarriage while the dipper is in-bank. Inparticular, the process 250 can perform a swing comparison step 290 inwhich the swing action 268 is compared to a swing threshold 292 receivedby the process. The swing threshold 292 may be a predetermined valuesuch as a minimum or maximum quantity or may be based on dynamicoperational characteristics associated with the mining shovel and/ormine site. In the embodiment where the swing action 268 corresponds tothe swing speed, the swing threshold 292 can correspond to a speed limitor the like. If the swing comparison step 290 confirms that the swingaction 268 exceeds the swing threshold 292, this may indicate theoperator is attempting to swing the upper structure with the dipperin-bank in an undesirable manner such as at an undesirable speed. Inanother embodiment, if the swing action 268 is significantly above theswing threshold 292, indicating that the operator is intentionallytrying to swing the mining shovel and the dipper is not likely in thebank, the swing comparison step allow the operator to continue swingingthe mining shovel accordingly. In such a case, the swing comparison step290 determines if the swing action 268 is below the swing threshold 292and should be limited.

In such a case, the process 250 can perform a swing limitation step 294in which the operator's ability to swing the upper structure can belimited or reduced below the normal capacity by, for example, a fixedpercentage such at 5% or 10%. In addition, the process 250 may provide avisual warning 296 or other warning that may display on the visualdisplay device informing the operator that the process is in the swinglimitation step 294. Limiting rotation of the upper structure with thedipper located in-bank further reduces bending moments that wouldotherwise be applied to the digging assembly if the operator attemptedto swing the upper structure a significant distance. Allowing limitedswinging further enables limited movement of the dipper assembly in aside-to-side motion, such as may be desirable to assist filling thedipper with material or to free a dipper stuck in the bank. In anotherembodiment, the process 250 may completely lock or block the ability ofthe operator to swing the upper structure for the duration of thein-bank condition. When the process 250 is no longer making an in-bankdetermination, it can proceed to a termination step 296 in which theprocess returns full swing capability to the operator.

INDUSTRIAL APPLICABILITY

The present disclosure describes a system and process for determiningthe approximate location of the dipper of a mining shovel or similarmining device including whether the dipper is located in-bank or inanother surface at a mine site. Referring to FIG. 1 and to FIG. 4, thedigging operation may be explained. FIG. 4, in particular, is a chart300 with forces 302 in, for example, foot-pounds or Newton-meters,represented on the Y-axis and time 304, for example in seconds,represented on the X-axis. FIG. 4 illustrates a digging operation inwhich the estimated position of the dipper, as represented by a dipperlocation line 310, is made in relation to the calculated crowd force 320according to the above equations. The positive and negative signsattributed to the forces 302 along the Y-axis, or the positive andnegative regions of the chart, are made in reference to the directionthe dipper assembly 130 is moving with the force increasing duringretraction and decreasing during crowding. Hence, the positive andnegative signs associated with the forces 302 should be interpreted as achange in the direction that the forces are applied to the crowd system160 rather than a change in the absolute force applied to the crowdsystem.

During the digging operation, the mining shovel 100 may initiallyretract and then crowd the dipper assembly 130 toward the bank 108 bytranslating the dipper arm 134 in the saddle block 140 backward andforward with respect to the boom 122 along the forward-reverse direction146. Prior to impacting the bank 108, the calculated crowd force 320,indicated in FIG. 4 as a rope force applied to the crowd ropes, may bepositive, as indicated by the first upward curve 322. This may bebecause the hoist system 150 at that time may be moving the dipperassembly 130 in the vertical direction 144, thereby assisting the crowdsystem 160, and because the torque output of the crowd motor 162 is onlymoving the dipper assembly through the empty space before the bank 108.Accordingly, the electronic controller on the mining shovel 100 mayrecognize the upward curve 322 as indicating the dipper 132 has notimpacted or penetrated into the bank 108, i.e., the dipper isout-of-bank. In FIG. 4, this out-of-bank condition may correspond to thefirst lower portion 312 of the dipper location line 310.

When the dipper 132 does impact the bank 108, the calculated crowd force320, as represented by the rope force such as tension or lack of tensionon the crowd ropes, sharply drops negative as indicated by the downwardcurve 324. This represents that the crowd system 160 is experiencingsignificant stresses that may even exceed the output torque of the crowdmotor 162. This downward curve 324 may continue as the dipper 132 isdisposed within and penetrates into the bank 108. In fact, the downwardcurve 324 may include a second downward peak 326 as the operatorsubsequently retracts and crowds the dipper assembly 130 into the bankto fill the dipper 132 with material. The operator may also bemanipulating the crowd system 160 to assist filling the dipper 132 withmaterial. The electronic controller, using the steps and calculationsdescribed above, interprets this as an in-bank condition as representedby the upper portion 314 of the dipper location line. For the durationof the upper portion 314, the electronic controller may implement theanti-swing function and restrict the ability to swing the upperstructure 104 with respect to the undercarriage 102 while the dipper 132is in-bank.

When the dipper 132 is filled and the mining shovel 100 retracts thedipper assembly 130 from the bank 108, the calculated crowd force 320 asapplied to the crowd ropes may increase into the positive region of thechart 300 as indicated by the second upward curve 328. The electroniccontroller may interpret this as meaning the dipper 132 is no longer inbank, as indicted by the second lower portion 316 of the dipper locationline 310. At this point, the electronic controller may release theanti-swing function and allow the upper structure 104 to swing about thevertical axis 170 to move the dipper 132 over a dump truck and unloadthe material. Hence, the present disclosure assists operation of themining shovel 100 by determining the approximate location of the dipper132 with respect to the bank 108 based on a calculated crowd force,rather than based on a different parameter such as crowd motor torquealone, which may not accurately correspond to the location of thedipper.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext.

Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

We claim:
 1. A mining machine comprising: an undercarriage; an upperstructure rotatably supported to swing with respect to theundercarriage; a digging assembly disposed on the upper structure, thedigging assembly including: a boom connected to the upper structure at alower end and extending upwardly to an upper end; a dipper assemblyincluding a dipper arm and a dipper disposed at a first end of thedipper arm, the dipper assembly slidably supported by the boom; a crowdsystem for slidably moving the dipper assembly with respect to the boomin a crowd direction and in a retract direction, the crowd systemincluding: a crowd motor disposed in the upper structure, a crowdactuator operatively associated with the crowd motor and arranged toslide the dipper arm with respect to the boom; and an electroniccontroller operatively associated with the crowd system and inelectronic communication with the crowd motor, the electronic controllerconfigured to receive a crowd speed and a crowd motor torque and tocalculate a calculated crowd force and to determine an approximatelocation of the dipper based on the calculated crowd force.
 2. Themining machine of claim 1, wherein the electronic controller receives aninertia parameter associated with the dipper assembly and calculates thecalculated crowd force based in part on the inertia parameter.
 3. Themining machine of claim 2, wherein the electronic controller convertsthe crowd speed to a crowd acceleration.
 4. The mining machine of claim3, wherein the electronic controller calculates an inertial crowd forcebased on the inertia parameter and the crowd acceleration.
 5. The miningmachine of claim 4, wherein the electronic controller calculates thecalculated crowd force by subtracting the inertial crowd force from thecrowd motor torque.
 6. The mining machine of claim 1, wherein theelectronic controller receives a crowd force threshold and compares thecrowd force threshold with the calculated crowd force to determine theapproximate location of the dipper.
 7. The mining machine of claim 1,wherein the electronic controller is further configured with ananti-swing function to restrict a swing speed of the upper structure. 8.The mining machine of claim 7, wherein the approximate location of thedipper maybe either one of an in-bank condition or an out-of-bankcondition.
 9. The mining machine of claim 8, wherein the anti-swingfunction restricts the swing speed during the in-bank condition only.10. The mining machine of claim 9, wherein the electronic controllercompares the calculated crowd force to a crowd force threshold todetermine if the in-bank condition exists.
 11. The mining machine ofclaim 1, wherein the crowd actuator includes one or more crowd ropesattached to the dipper arm and disposed about a crowd drum disposed inthe upper structure.
 12. The mining machine of claim 11, wherein the oneor more crowd ropes include a first crowd rope attached proximate afirst end of the dipper arm and a second crowd rope attached proximate asecond end of the dipper arm.
 13. The mining machine of claim 1, whereinthe crowd actuator is a hydraulic cylinder.
 14. A method of operating amining machine comprising: sliding a dipper assembly in translation withrespect to a boom arranged in an upward orientation on the miningmachine by operation of a crowd motor; receiving a crowd motor torqueand a crowd speed; receiving an inertia parameter associated with thedipper assembly; calculating a calculated crowd force based in part onthe crowd motor torque, the crowd speed, and the inertia parameter; anddetermining an approximate location of a dipper disposed on the dipperassembly based on the calculated crowd force.
 15. The method of claim14, further comprising converting the crowd speed to a crowdacceleration.
 16. The method of claim 15, wherein the step ofcalculating the calculated crowd force include determining an inertialcrowd force from the crowd acceleration and the inertia parameter, andsubtracting the inertia force from the crowd motor torque.
 17. Themethod of claim 14, wherein the approximate location of the dipperincludes at least one of an in-bank condition and an out-of-bankcondition.
 18. The method of claim 17, further comprising limiting aswing ability of an upper structure with respect to an undercarriageduring the in-bank condition.
 19. An electronic controller for a miningmachine having a dipper assembly slidably supported on a boom extendingupwardly with respect to the mining machine, the electronic controllercomprising: a crowd force function configured to determine a calculatedcrowd force based in part on a crowd motor torque generated by a crowdmotor arranged to slide the dipper assembly with respect to the boom, acrowd speed of the dipper assembly sliding with respect to the boom, andan inertia parameter associated with the dipper assembly; the crowdforce function further configured to determine an approximate locationof a dipper disposed on the dipper assembly based on the calculatedcrowd force, the approximate location including at least one of anin-bank condition and an out-of-bank condition; and an anti-swingfunction configured to limit rotation of an upper structure with respectto an undercarriage about a vertical axis of the mining machine duringthe in-bank condition.
 20. The electronic controller of claim 19,wherein the crowd force function is further configured to convert thecrowd speed to a crowd acceleration.